Friction stir welding (FSW) is a welding process that uses heat generated from high-pressure friction to form a joint between two workpieces and/or to fix cracks in a workpiece. That is, during FSW operations, an FSW tool traverses a joint or seam disposed between the workpieces (or a crack in a workpiece) and the one or more workpieces are plasticized by frictional heat generated by rotation of the FSW tool. As the FSW tool traverses the seam, the FSW tool is also pressed against the one or more workpieces. More specifically, during a welding operation, a shoulder is pressed against the workpiece(s) and a pin rotates in the seam between the workpieces (or in a crack in a workpiece). In some FSW heads, the shoulder rotates with or relative to the pin, but in other FSW heads, the shoulder may be stationary. Rotation of the pin (and the shoulder in some instances), softens and mixes the materials forming the workpieces. Then, the mixed materials consolidate to form a solid-state weld.
An FSW tool (which may include the pin and the shoulder) can traverse a seam (or crack) when its FSW head moves relative to the workpiece(s) and/or when the workpiece(s) are moved relative to the welding tool (e.g., the welding tool may be stationary). Regardless, as a FSW tool welds a seam, the friction between the FSW tool and the workpiece(s), the softening of the workpieces(s) causes at least some material to be extruded away from the workpieces as “flash.” For example, often, a circumferential collar of extruded material rolls back from the FSW tool to form a configuration resembling a ram's horn, which is commonly referred to as a bifurcated flash formation. Consequently, to finish a FSW weld, the flash must be removed from the workpiece(s).
Often, the flash is removed with milling or grinding processes that traverse the seam after the FSW tool. For example, after welding a seam, a FSW tool can be removed from a rotary machine and replaced with a milling tool so that the rotary machine can remove the flash during a second pass over the weld. Alternatively, a user can mill the flash with a milling tool that is separate and distinct from the FSW machine. However, each of these options lengthens the takt time (e.g., the rate of production) for a particular job. Still further, some FSW welding heads have incorporated blades that can remove (e.g., cut) flash from a weld seam as the FSW welding head traverses the seam; however, often these blades scatter chips (i.e., pieces of flash) throughout the workplace. Not only does this scattering of chips create a mess, but also in some instances, the chips may enter the FSW machine and force an end-user to clean the machine. Alternatively, the chips might adhere to a part of the weld seam that has yet to full coalesce, negating the blade's attempt to remove the flash from the seam.